In general, a semiconductor power device mainly used for a system, such as a motor control system or a power conversion system, in various power electronics fields is watched with interest.
As this type of semiconductor power device, an SiC semiconductor device having a trench gate structure is proposed, for example.
For example, FIG. 1 of Patent Document 1 discloses a MOS semiconductor device having an SiC substrate (1), an n-type high-resistance layer (2) formed on the SiC substrate (1), a p well layer (3) formed on the n-type high-resistance layer (2), an n+ emitter region (8) formed on a surface layer portion of the p well layer (3), a p+ contact region (12) passing through the n+ emitter region (8) and reaching the p well layer (3), a trench (5) passing through the p well layer (3) from a front surface of the n+ emitter region (8) and reaching the n-type high-resistance layer (2), a gate oxide film (6) formed on an inner surface of the trench (5), and a polysilicon gate electrode (7) embedded in the trench (5) (refer to Patent Document 1, for example).